Susan Schneider Williams, widow of Robin Williams, is speaking out about her experience with Lewy body dementia — the disease that led to her husband's suicide.

"Looking back, I see that weekend, that time frame, as really the beginning of what became just a firestorm of symptoms that started raining down on Robin," Schneider Williams said during a podcast interview with Dr. Ted Burns.

In an open letter, Schneider Williams wrote of the years leading up to her husband's death and what she calls "the terrorist" inside his head.

Lewy body dementia is a degenerative disease that can cause hallucinations, memory loss and anxiety, among other symptoms. It's closely related to Parkinson's disease, which Williams was diagnosed with in May 2014.